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Biomedical subjects

H Mishima

Publications and source records attributed to H Mishima.

At least 181 records · Page 10Linked to original sources
PubMed1980

Milbemycins, a new family of macrolide antibiotics: fermentation, isolation and physico-chemical properties.

A search for novel insecticides has yielded the milbemycins, a new family of macrolide antibiotics with insecticidal and acaricidal activity. They are produced in submerged cultures of Streptomyces hygroscopicus subsp. aureolacrimosus. Fermentation studies on the strain were conducted in shaken flasks and 30-liter jar fermentors. From the culture broth 13 milbemycins were purified to homogeneity by column and thin-layer chromatography on silica gel and alumina. Physico-chemical data, such as mass spectra, UV and IR absorption spectra, optical rotations and melting points of the milbemycins are described.

Anti-Bacterial Agents↗
PubMed1979

Fine structural demonstration of tyrosinase activity in the retinal pigment epithelium of normal and PTU-treated chick embryos.

The effect of phenylthiourea (PTU) on the retinal pigment epithelium of chick embryo was studied by using electron microscopy and electron-microscopic histochemistry. In the retinal pigment epithelium of PTU-treated, 10-day-old chick embryo, there is an abundance of premelanosomes and relative increases in the smooth endoplasmic reticulum (ER), and in the smooth-surfaced anastomosing tubular channels. Reaction products resulting from electron-microscopic histochemistry are first observed in some cisternae of the distal or active face of the Golgi apparatus and occasionally in small vesicles in the 5-day-old embryo, and these reactions become more intense with time. PTU treatment blocks melanin synthesis in the premelanosomes of 10-day-old chick embryo. Electron-microscopic histochemistry is completely inhibited by PTU treatment. Removal of PTU allows a weak positive reaction to histochemistry in some elements of the Golgi apparatus and in some small vesicles.

Animals↗
PubMed1978

Some observations in the fine structure of age changes of the mouse retinal pigment epithelium.

Age changes of the fine structure in the CF-1 mouse retinal pigment epithelium were studied from 1--24 months old. The change most characteristic of the senescence of the retinal pigment epithelium was found to be the appearance of wavy undulating 12nm wide filaments having a periodicity of about 80nm after the 12th month. In addition, the retinal pigment epithelial cells of the aging eye were found to have a marked accumulation of lysosomal dense bodies measuring about 0.3 to 1.2 micrometer in diameter especially in the apical portion of the cytoplasm. Extended and enlarged basal cytoplasmic infoldings of the retinal pigment epithelial cells were another prominent age change in the old mouse. In these basal infoldings densely fixed amorphous materials by tannic acid and very fine filaments are recognized. Age-related changes of the retinal pigment epithelial cell of the CF-1 mouse may take place as the degeneration of cytoplasmic materials, the appearance of bundles consisting of parallel undulating filaments, and the extending process of basal infolding from the choroid side.

Aging↗
PubMed1978

Studies on the cytodifferentiation of the neuroblasts and visual cells in the chick embryo retina, using the electron-microscopic autoradiography of 3H-thymidine.

Studies on the histogenetic analysis of cytodifferentiation of the neuroblast and visual cell in the chick embryo retina were made using the autoradiography of 3H-thymidine. The posterior pole region of the eyeball was observed in all the animals used. The retina in a 4-day-old chick embryo consists exclusively of matrix cells forming the matrix layer. In a 5-day-old chick embryo retina, neuroblasts first differentiated from the matrix cells migrate into the outer part of the matrix layer, forming mantle layer. The matrix cell is a homogeneous epithelial cell containing abundant free ribosomes and a poorly developed cytoplasmic membrane system in the cytoplasm. The characteristic sign of differentiation of the neuroblast is an appearance of elements of rough-surfaced endoplasmic reticulum and an indentation of the nucleus. The primitive visual cell having just lost its ability to synthesize DNA appears just beneath the pigment epithelium in a 7-day-old chick embryo, and all the cells lying beneath the pigment epithelium lose the ability to synthesize DNA at 10 days of incubation. The cytoplasmic process of the matrix cell is in contact with the adjacent one, making an apicolateral junction. When the matrix cell loses its ability to synthesize DNA, a big tentlike process extending over the level of the apicolateral junction appears. This phenomenon is considered to be a sign of differentiation from matrix cell to primitive visual cell, and this big tentlike process containing 2 centrioles is a primordium of the inner segment of the visual cell.

Animals↗